1. Field of the Invention
This invention relates to document management, and in particular, it relates to a method for determining the authenticity of a digital document after it has been printed and then scanned in a closed-loop process.
2. Description of Related Art
A closed-loop process refers to printing an original digital document (which may include text, graphics, images, etc.), using the printed hard copy of the document such as distributing it, copying it, etc., and then scanning a hard copy of the document back into digital form. Authenticating a scanned digital document refers to determining whether the scanned document is an authentic copy of the original digital document, i.e., whether the document has been altered while it was in the hard copy form. Certain proposed method of authenticating a scanned document performs an image comparison of the scanned document with the original digital document. Such a comparison may be difficult to achieve to adequate accuracy due to various distortions to the original digital image during the print and scan process.